CN1863985A - Improvements in and relating to perforators - Google Patents

Abstract

A carrier (11) for at least one shaped charge (17), the carrier being disposable in use within an oil, gas, water or steam well bore. The carrier comprises a housing at least partially formed from a composite material which is non-frangible in normal use. The composite material component of the housing is arranged substantially to contain debris created within the carrier as a result of firing of the at least one shaped charge. The housing may be entirely of composite material or may comprise in inner metallic housing (14) and an outer overwrap (16) of composite material.

Description

Perforator and its improvement

technical field

The present invention relates to a perforating gun or carrier for perforating charges used in perforating and fracturing completions, particularly but not exclusively oil, gas, water and steam well completions.

Background technique

To date, the most important process for completing wells in cased holes has been to provide a flow path between the producing zone (also known as the formation) and the wellbore. Typically, this flow path is created using a perforator that creates perforations in the casing and physically penetrates the formation through the cement layer, commonly referred to as perforating. Although mechanical perforating devices exist, nearly all perforating is accomplished using high energy materials such as high explosives. The energetic material also has other benefits in that it stimulates the well in the sense that the shock wave introduced into the formation increases the efficiency of perforation and increases flow within the formation. Typically, such perforators take the form of shaped charges. Unless otherwise defined, perforating guns below shall refer to shaped charge perforators.

A shaped charge is a high-energy device consisting of an axisymmetric shell into which a liner is inserted. The liner provides the inner surface of one space, and the remaining inner surface of the space is provided by the shell. The space is filled with a high explosive such as HMX, RDX (cyclone explosive), PYX or HNS which, when ignited, collapses the liner material and shoots out of the casing in a high velocity material jet. The impingement of the jet of material creates a perforation in the wellbore casing, which is then passed into the formation. Typically, a large number of perforations are required for a particular casing zone near the formation. To do this, a perforating gun is run into the casing by wireline, coiled tubing, or other techniques known to those skilled in the art. The perforating gun described is actually a carrier for multiple perforating guns, which may have the same or different outputs. The precise type and number of perforators and the size of the perforating guns are usually determined by the completion engineer based on analysis and/or evaluation of the completion characteristics. Depending on the nature of the formation, the goal of the completion engineer is to achieve as many perforations as possible in the casing or to penetrate the surrounding formation as deeply as possible. Therefore, in unconsolidated formations, the former is more preferable, while in tight formations the latter is more needed. It will be appreciated that different formation properties require different completions and different degrees of specific completions.

Typically, the number and arrangement of charges within the perforating gun and the type of perforating gun are left to the completion engineer's choice. The constraint on the engineer and his choice of charge is the carrier or gun that delivers the perforations into the well. The carrier is a container used to limit the explosive force to the extent necessary not to rupture the wellbore casing. The carrier also acts as a barrier between the high pressure fluid in the well and the perforating charges. Much the same, steel was the material of choice for the production of the carrier. Therefore, the carrier is heavy and difficult to attach and detach.

Completion engineers will make decisions based on empirical methods derived from knowledge and understanding of the formations to be completed. However, to assist the engineer in making this selection, a range of tests and procedures have been developed that correspond to the performance characteristics of the perforator. These tests and procedures have been developed industrially by the American Petroleum Institute (API). In this regard, according to the www.api.org website, the API standard RP 19B (formerly RP 435 ^th edition) currently used downhole is widely used as an indication of perforator performance. Perforator manufacturers often use API standards to buy and sell their products. As a result, completion engineers are able to choose between perforating guns from different manufacturers that are deemed capable of performing a particular job. During the selection process, engineers can identify the type of perforator performance required.

However, despite these tests and procedures, it should be recognized that completion engineering remains essentially more art than science. The inventors presenting the present invention have recognized that the conservative nature of current well completion methods has failed to produce changes in the need for completion engineering methods to enhance and increase production through straightforward and complex completions.

Another problem with perforating guns is that debris remains in the well after the charge is fired. One way to solve this problem is to use a barrel or other carrier that is essentially destroyed after the charge is fired. Patent application GB2,365,468A (Sclumberger) discloses a device in which the barrel is formed of a composite material that is brittle under dynamic impact, so that it shatters after the detonation of the perforating charge; patent application GB2,380,536A (Sclumberger) A holster is disclosed which is combustible upon detonation of a perforating charge; and patent US 5,960,894 discloses a tube which in use breaks or burns without leaving large fragments in the well.

Patent application WO01/07860A3 discloses a device and a method for reducing disturbances generated by perforating charges.

Contents of the invention

Accordingly, according to a first aspect of the present invention there is provided a carrier for at least one shaped charge disposable in a wellbore, said carrier comprising at least partly a composite A casing constructed of a material, said composite material being a material that is not brittle in normal use, and said composite material being substantially configured to contain the fire produced within the carrier by the ignition of at least one shaped charge debris.

In a preferred embodiment of the carrier, the housing comprises an inner shell at least partially surrounded by an outer composite cover layer. Preferably, the inner shell is substantially metallic in construction.

Preferably, the inner shell is in the form of a thin-walled metal cylinder. Usually high strength steel is used. Advantageously, the thickness of the metal cylinder is less than that of a conventional carrier constructed entirely of metal. This reduction in thickness enables weight savings.

Providing a composite cover enhances the performance of the carrier. In general, the selection of the physical characteristics of the composite material can match the needs of the carrier, and the selection of the physical characteristics of the composite material means the selection of the material and/or the selection of the composite material structure. In particular, it is desirable that the axial and annular properties of the composite blanket be independently transferable to address stress distribution during carrier loading and unloading and spontaneous firing of one or more charges. Beneficially, the axial flexibility of the carrier may facilitate easier routing of the carrier into the well and through inclined sections therein. It may be preferred that the fiber tension of the composite material is such that it minimizes the extent of expansive detonation energy dissipated during detonation of the one or more perforating charges. Piloting or igniting the charge may result in localized pressurization/shock, which inflates or expands the carrier. Overexpansion of the carrier can cause the carrier to become lodged in the wellbore casing with significant adverse effects. Accordingly, the carrier of the present invention utilizes larger and/or more perforating charges than conventional carriers of the same size in use today.

In a preferred embodiment, the housing is constructed entirely or substantially entirely of composite material.

Whether all or part of the casing or overburden, the composite material is chosen such that fragmentation of the composite material occurs only when required to limit pressurization and/or impact external to the carrier or completion. In this case, the composite is inherently non-brittle within the range of operating parameters typically required. Thus, the composite portion of the carrier remains stationary while the gun is fired, thereby retaining fragments produced by the shaped charge. As a result, nearly all of the perforating gun residue can be recovered from the well after the gun is fired.

According to another aspect of the invention there is provided a perforating gun comprising a carrier according to the invention.

According to another aspect of the present invention, there is provided a method of improving fluid flow from a wellbore, the method comprising the steps of: providing a perforating gun (or carrier for a perforating gun) of the present invention; disposed within the wellbore; perforating the wellbore by igniting the perforating gun; retrieving debris produced by the perforating step by retrieving a carrier of the perforating gun containing the debris produced by the firing.

Beneficially, subsequent production of fluids (such as hydrocarbons (oil or gas), water or steam) from the well is improved as the carrier facilitates improved containment and recovery of debris from the well. As a result, less debris is left in the well to prevent the outflow of fluids, and less debris can become trapped in the outgoing fluid, which can subsequently plug and corrode wellhead tubing and equipment.

Description of drawings

In order to help understand the present invention, several embodiments of the present invention will now be described in conjunction with examples and accompanying drawings, wherein:

Figure 1 is a cross-sectional view of a well completion showing a perforating gun or carrier in accordance with an embodiment of the present invention;

Figure 2 is a side view, partly in section, of a perforating gun or carrier according to the first aspect of the invention;

Fig. 3 is a cross-sectional view of the carrier in Fig. 2 along the line III-III in Fig. 2;

Figure 4 is a side view, partially in section, of a perforating gun or carrier according to another aspect of the invention.

Detailed ways

In the description that follows, the carrier or gun will be interchangeable.

Referring to Fig. 1, which shows the completion stage of well 1, wellbore 3 has been drilled into two production zones 5, 7, which are unconsolidated formation and tight formation respectively. Steel pipe or steel casing is cemented in the wellbore 3, and in order to provide a flow path from the production zones 5, 7 into the final annulus, it is necessary to perforate the casing 9, which is formed in the casing 9 and the production tubing (not shown) present in the completed well. To form perforations in the casing 9, perforating guns 11 are lowered into the casing by means of suitable cables, wires or flexible tubing 13.

As shown in Figures 2 and 3, which show in more detail that the perforating gun 11 includes a steel inner cylindrical tube 14 having an orifice 15 therein through which the The perforating charges 17 in the gun body of the perforating gun 11 are ignited. Surrounding the inner cylindrical tube 14 is a composite cover 16 . Said cover layer 16 effectively constitutes an outer cylindrical tube in which corresponding openings 15 to those in the inner cylindrical tube 14 are provided.

The overall diameter of the perforating gun 11 is selected to form a tight but non-interfering fit with the casing 9 as shown in FIG. 1 . Thus, the perforating gun 11 is effectively self-centering within the casing 9 . By having the gun self-centering within the casing 9 there is little or minimal variation in offset between the charges 17 and the casing 9 . Significant variations in any offset distance can have a detrimental effect on the consistency of perforating charge 17 performance.

In use, the perforating gun 11 is lowered into the well 1 at a depth adjacent to the production zones 5,7. The pay zones 5, 7 may extend beyond the length of the perforating guns 11, in which case a string of perforating guns may be lowered into the well and/or multiple operations may be required to casing the pay zones . Furthermore, if the formation is unconsolidated, the charges 17 tend to form larger perforations in the casing 9 at the expense of the depth of penetration into the formation. Conversely, smaller perforations can be formed in the casing 9, for example in highly dense formations where greater penetration depths are required. In both cases, the completion engineer will try to select the most suitable charge for the particular perforation required by the casing 9 .

Turning now to Figure 4, another embodiment is shown in which the entire perforating gun 11' is constructed from a thin walled cylinder 16' of composite material. The barrel has an orifice 15' and a suitable fixing point for receiving a charge 17' within the barrel gun body.

Composite materials used on the cladding of the steel cylinder 14 or on the frangible overall perforating gun 11 are selected to provide additional strength in terms of physical performance improvements of the perforating gun. Thus, composite materials may be constructed of reinforced polymeric materials. Some non-limiting reinforcement examples include various embodiments of performing a reinforcement operation or using individual rovings.

Such operations include fabrication using hand winding, filament winding, compression molding, or using binder braid to maintain the desired shape, to name just four examples. The solid material filler is added to the matrix material, which may comprise one or more plastic materials. The plastic material may be selected from, but not limited to, one or more of the following types: thermosetting plastics, thermoplastics and elastomers. As can be appreciated, the choice of plastic material depends largely on the temperature of the completion operation. In some cases, the perforating gun 11 may remain within the casing 9 for a period of time before use. Therefore, said plastic material must not only be able to withstand a temperature rise of about 200° C. but also high temperature operation for significant periods of days or even weeks.

It has been determined that different classes of thermoplastics, such as polystyrene, polyolefins containing 2 to 10 carbon atoms, such as polyethylene and polypropylene, can withstand temperatures of about 200°C. Above this temperature, plastic materials with higher melting points such as polyethersulfone (PES), polyoxymethylene (POM) and PK can be used.

As mentioned above, filler materials may be added to the matrix material. The filler material may include one or more preferred metallic materials. For example, the metal material can be selected from the following non-limiting materials: copper, aluminum, iron, tungsten, and alloys thereof. Additionally or alternatively, non-metallic materials may be selected. These materials include, but are not limited to, inorganic or organic materials such as borides, carbides, oxides, nitrides of metals and glasses, especially refractory metals.

As previously mentioned, it has been found that fragments of prior art perforating guns produced by the detonating action of one or more perforating charges 17 can produce indirect damage to the structure of the formation 5, 7 surrounding the perforating gun. Such prior art gun fragments can be carried by well fluids into valves and the like where they can accumulate and/or corrode, especially in guns made of zinc. Therefore, a different form of the second described embodiment is proposed, which should be based on the energy of the perforating gun to break into undersized fragments and cause significant damage to surrounding structures or well equipment if excessive energy is released by the detonation of the perforating charge. Select the composite material. Fragile materials are selected so that fragments are generated only when the gun is overcharged or intentionally when the charge is fired. In the latter case, the perforating guns refer to single-use perforating guns and perforating guns that can also be charged with perforating charges, which when fired will themselves produce fragments that will not cause significant damage to the surrounding structure. .

It will be appreciated by those skilled in the art that methods of producing composite elements suitable for use in the perforating gun embodiments described above may be selected from the following non-limiting list. Therefore, the matrix using particle reinforcement is made by mixing these two material mixtures under vacuum. Coverings for perforating guns or composite thermoplastic granular materials can be made by injection molding and compression molding. Injection molding is considered to be particularly suitable for making perforating guns in dry conditions. Compression molding can be effective for perforating guns or cover layers containing thermoplastic fibers mixed with reinforcement materials.

This method provides good strength and dimensional accuracy for perforating guns or carriers made by filament winding.

Claims (15)

1. carrier that is used at least one lined-cavity charge, described carrier can disposable use in pit shaft, described carrier comprises the housing of being made by composite material at least in part, described composite material is non-friable in common use, and described composite material is arranged on substantially and holds because described at least one lined-cavity charge of igniting and the fragment that produces in carrier.

2. the described carrier of arbitrary as described above claim, it is characterized in that: described housing comprises inner casing, described inner casing is surrounded by outside composite material overwrap at least in part.

3. carrier as claimed in claim 2 is characterized in that: described inner casing is metal basically.

4. carrier as claimed in claim 1 is characterized in that: described housing is a composite material casing.

5. the described carrier of arbitrary as described above claim, it is characterized in that: described housing has thin cylinder.

6. the described carrier of arbitrary as described above claim, it is characterized in that: described housing has the thin-wall metal cylinder.

7. the described carrier of arbitrary as described above claim is characterized in that: form at least one aperture in the described carrier.

8. the described carrier of arbitrary as described above claim is characterized in that: a plurality of apertures distribute along the longitudinal length of carrier.

9. the described carrier of arbitrary as described above claim is characterized in that: described composite material is the polymer substrate of filler.

10. the described carrier of arbitrary as described above claim, it is characterized in that: described composite material comprises the fiber of vertical setting.

11. the described carrier of arbitrary as described above claim, it is characterized in that: described composite material comprises the fiber of circumferential setting.

12. carrier as claimed in claim 10 is characterized in that: the fiber of described circumferential setting has default tension force respectively.

13. perforating gun that comprises the described carrier of aforementioned arbitrary claim.

14. one kind is improved the method that fluid flows out from pit shaft, described method comprises step:

The described perforating gun of claim 13 carrier of perforating gun (or be used for) is provided;

Described perforating gun is positioned in the pit shaft;

By the igniting perforating gun pit shaft is carried out perforation;

Regain the fragment that is produced by the perforation step by the carrier that reclaims perforating gun, described carrier accommodates the fragment that is produced by igniting.

15. method as claimed in claim 14 is characterized in that: described fluid is one or more in hydro carbons, water and the steam.